Spin-current noise and Bell inequalities in a realistic superconductor-quantum dot entangler

Olivier Sauret, Thierry Martin, and Denis Feinberg
Phys. Rev. B 72, 024544 – Published 28 July 2005

Abstract

Charge and spin current correlations are analyzed in a source of spin-entangled electrons built from a superconductor and two quantum dots in parallel. In addition to the ideal (crossed Andreev) channel, parasitic channels (direct Andreev and cotunneling) and spin flip processes are fully described in a density matrix framework. The way they reduce both the efficiency and the fidelity of the entangler is quantitatively described by analyzing the zero-frequency noise correlations of charge current as well as spin current in the two output branches. Spin current noise is characterized by a spin Fano factor, equal to 0 (total current noise) and 1 (crossed correlations) for an ideal entangler. The violation of the Bell inequalities, as a test of nonlocality (entanglement) of split pairs, is formulated in terms of the correlations of electron charge and spin numbers counted in a specific time window τ. The efficiency of the test is analyzed, comparing τ to the various time scales in the entangler operation.

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  • Received 27 May 2005

DOI:https://doi.org/10.1103/PhysRevB.72.024544

©2005 American Physical Society

Authors & Affiliations

Olivier Sauret1,*, Thierry Martin2, and Denis Feinberg1

  • 1Laboratoire d’Etudes des Propriétés Electroniques des Solides, CNRS, BP 166, 38042 Grenoble Cedex 9, France
  • 2Centre de Physique Théorique, Université de la Méditerranée, Case 907, 13288 Marseille, France

  • *Present address: Department of Theoretical Physics, Budapest University of Technology and Economics, Budapest, Hungary.

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Vol. 72, Iss. 2 — 1 July 2005

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